The present invention relates to a printed circuit board for use in electrical and electronic appliances and more particularly, to a printed circuit board which is arranged to connect cross pattern electrically conductive layers disposed on X-Y cross coordinates on the circuit board by an electronic part or component as a jumper without shortcircuiting therebetween.
Generally, in cases where cross pattern electrically conductive layers are to be crossed over each other on X-Y cross coordinates on a printed circuit board, it has been so arranged as shown in FIG. 1 that one set of conductive layers Ca of sets of conductive layers Ca and Cb which are to be crossed over on the reverse surface of a printed circuit board P is laid or wired continuously without cutting or separation on the way, and the other set of the conductive layers Cb which is to be crossed over the one set of conductive layers Ca is separated or discontinued to be disposed to confront the layers Ca, while jumper electronic parts j are provided between respective confronting portions of the conductive layers Cb through bonding agent b for crossing over by soldering based on the known solder dipping method so as to avoid shortcircuiting between the conductive layers Ca and Cb thus crossed over each other.
The conventional crossover arrangement as described above, however, has such drawbacks that, if the number of cross pattern portions is increased or concentrated on the printed circuit board P, large spaces are occupied thereon by the increased number of the jumper electric parts j, thus reducing spaces for mounting other electronic parts such as leadless chip parts, discrete electronic parts, etc. on the printed circuit board.
Meanwhile, for avoiding an increase of the number of cross pattern portions on the printed circuit board, there has conventionally been proposed another arrangement in which other conductive layers (not shown) are provided for connecting the cut or separated conductive layers Cb of the layers Ca and Cb on the front surface of the printed circuit board P so as to couple such other conductive layers with the conductive layers Cb via through-holes formed in the circuit board P. The known arrangement as described above, however, still has such disadvantages that the connections at the through-holes are undesirably cut off or broken by shock in heating, heating cycles or repeated heatings, etc. during soldering of other electronic parts such as leadless chip parts, discrete electronic parts, etc. to the printed circuit board, thus not being suitable for actual application.